Effects of Drying Temperature on the Drying Characteristics of Parboiled Palm Nuts

Abstract

The effect of drying temperature on drying characteristics of cooked and fermented palm nuts were determined. The samples were processed using two methods (cooking and fermentation). The rate of drying the samples was observed to increase with corresponding increase in temperature and drying time. It was duly observed that at 70C, Tenera sample (TS), Pisifera sample (PS) and Dura sample (DS) attained their constant drying rates at 720 mins, 600 mins, and 780 mins. At 80C TS, PS and DS drying rates falls to zero at 660mins, 600 mins and 720 mins, for 90C drying temperature, TS and PS had same constant drying rate at 540 mins, DS constant drying rate was found at 600mins. For 100C TS constant drying rates was observed at 480mins while PS and DS had same constant drying rate at 420mins respectively. The effective drying of the samples was observed to occur at falling rate across the varieties and processing methods. The lower temperature (70C) decreased the drying rates while the higher temperature increased the drying rates. The average drying time for cooked samples irrespective of sample varieties were 740 mins, 620 mins, 460 mins and 500 mins for temperature range of 70-100C respectively while for the fermented samples, the average drying time were 680 mins, 660 mins, 560 mins and 440 mins at temperature range of 70-100C respectively. The regression equations were found to give the best fit with highest coefficient of variation (R2) values. Mostly all the samples irrespective of processing methods exhibited quadratic regression equations. The cooked samples displayed better dry characteristics than fermented samples.